1. Field of This Invention
This invention relates to a process for the production of 2-vinyl pyridine.
2. Prior Art
It is generally known that 2-vinyl pyridine can be produced in a two-step reaction from 2-picoline and formaldehyde by way of 2-(.beta.-hydroxyethyl)-pyridine as the intermediate. For carrying out such reactions, numerous processes have been developed. The processes, among other things, differ in that the basic reactions were carried out by stages or in a single process step. A particular disadvantage of these processes is that, in order to guarantee a sufficiently selective reaction course in the first reaction step, 2-picoline must be used in an excess of 100 to 500 percent (see British Pat. No. 850,114 and West German Pat. No. 2,002,661).
With other production processes, which are based on catalytic dehydration of 2-ethyl pyridine, complete isolation of 2-vinyl pyridine is cumbersome and expensive because the boiling points of the educt and end product are very close (see Ullmanns Encyclopedia of Technical Chemistry, Third Edition, No. 18, 103).
In addition, it is also known to produce 2-vinyl pyridine from acrylonitrile and acetylene (see Swiss Patent Application No. 12139/75). In such case, the reaction takes place with the help of a catalyst which forms from cobaltocene. Unfortunately, cobaltocene or the catalyst which forms from it causes undesirable polymerization [see Mem. Inst. and Ind. Res., Osaka Univ., Vol. 28, 113, (1971)]. As a result, 2-vinyl pyridine is obtained only in a yield of 34.4 percent.